From 93cd7684ee2bba227fa371daa81b88f25456dcb2 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Mon, 3 Apr 2017 22:24:17 -0400 Subject: [PATCH] Properly acquire buffer lock for page-at-a-time hash vacuum. In a couple of places, _hash_kill_items was mistakenly called with the buffer lock not held. Repair. Ashutosh Sharma, per a report from Andreas Seltenreich Discussion: http://postgr.es/m/87o9wo8o0j.fsf@credativ.de --- src/backend/access/hash/hash.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c index 34cc08f12d..b835f772d4 100644 --- a/src/backend/access/hash/hash.c +++ b/src/backend/access/hash/hash.c @@ -476,9 +476,17 @@ hashrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys, HashScanOpaque so = (HashScanOpaque) scan->opaque; Relation rel = scan->indexRelation; - /* Before leaving current page, deal with any killed items */ + /* + * Before leaving current page, deal with any killed items. + * Also, ensure that we acquire lock on current page before + * calling _hash_kill_items. + */ if (so->numKilled > 0) + { + LockBuffer(so->hashso_curbuf, BUFFER_LOCK_SHARE); _hash_kill_items(scan); + LockBuffer(so->hashso_curbuf, BUFFER_LOCK_UNLOCK); + } _hash_dropscanbuf(rel, so); @@ -507,9 +515,17 @@ hashendscan(IndexScanDesc scan) HashScanOpaque so = (HashScanOpaque) scan->opaque; Relation rel = scan->indexRelation; - /* Before leaving current page, deal with any killed items */ + /* + * Before leaving current page, deal with any killed items. + * Also, ensure that we acquire lock on current page before + * calling _hash_kill_items. + */ if (so->numKilled > 0) + { + LockBuffer(so->hashso_curbuf, BUFFER_LOCK_SHARE); _hash_kill_items(scan); + LockBuffer(so->hashso_curbuf, BUFFER_LOCK_UNLOCK); + } _hash_dropscanbuf(rel, so); -- 2.40.0